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Insomnia with predominant thalamic involvement and minor cortical and cerebellar pathologic changes is not characteristic of familial Creutzfeldt–Jakob disease (CJD) but is a hallmark of fatal familial insomnia.

The mouse autosomal recessive mutant gene weaver (wv) results in abnormalities in cerebellum, substantia nigra and testis. Although a subtracted cDNA library prepared by removing P31 (wv/wv) sequences from a P1 (wv/+) library should contain mainly nonrepetitive neonatal sequences, unfortunately, repetitive sequences still appear during screening. Two clones, one repetitive, the other not, are used to illustrate the problems encountered in attempting to isolate the weaver gene from a subtracted cDNA library.

Tyrosine hydroxylase activity was assayed in microdissected substantia nigra and striata from seven strains of mice (BALB, CBA, YBR, WB, IS, MOLG, and CAST). In the substantia nigra where tyrosine hydroxylase activity is thought to be proportional to dopaminergic neuron number, only CBA had a different (lower) enzyme activity compared with BALB. However in the striatum, tyrosine hydroxylase activity was larger for IS, MOLG and CAST compared with BALB. Further investigation of the CAST striatum showed that dopamine content and dopamine uptake activity were also higher in comparison with BALB. All three dopaminergic parameters were larger because of lower protein levels in the CAST striatum. A lower absolute amount of glutamic acid decarboxylase activity in CAST versus BALB striatum was consistent with the possibility of a smaller CAST striatum. In contrast to dopamine, the serotonin content in CAST striatum was reduced in proportion to the decrease in protein content. We suggest that the CAST striatum is smaller than BALB striatum and is innervated by proportionally fewer serotoninergic terminals, but the amount of dopaminergic innervation of the CAST striatum is not altered by the size of the target.

Summary Weaver (wv/wv) mutant mice lose most granule cells of the cerebellum during the first 2 weeks of postnatal life; ‘Purkinje cell degeneration’ (pcd/pcd) mutants lose virtually all Purkinje cells between postnatal days 17 and 45. Both these neurological mutations are autosomal recessive. We designed a breeding protocol that, in theory, should result in the production of mice with a doubly mutant,wv/wv*pcd/pcd, genotype. Some of the offspring of such crosses had a novel cerebellar phenotype in which both granule and Purkinje cells underwent degeneration, leading to a highly atrophic cortex. This phenotype is what would be expected inwv/wv*pcd/pcd double mutants, and the proportion of such progeny obtained fits with genetic expectations. We propose that (1)wv/wv*pcd/pcd double mutant mice are viable, and (2) the anatomical phenotype of such mice is a combined expression of the component phenotypes.

An Indiana family segregating a syndrome of X-linked mental retardation and skeletal anomalies was tested for linkage of the mutant gene to X-chromosome molecular markers. Lod scores of 3.27 and 3.06 (T-0) for the molecular probes St14-1 (DXS52) and Dx13 (DXS15), respectively, indicate that the disease gene is located in the terminal portion of Xq.

We have searched for genetic variation in the expression of salivary androgen-binding protein (ABP) in a wide variety of mice and other rodents. ABP was present in the salivas of mice of all species and subspecies studied. Genetic studies have identified three common variants of the ABP Alpha subunit (Abpaa, Abpab, and Abpac) in Mus musculus populations with distributions that correspond roughly to those of the subspecies studied (domesticus, musculus, and castaneus, respectively). It appears that the ABP a and b polymorphisms conform to the hybrid zone between the domesticus and musculus subspecies characterized by others. Our studies suggest that the presence of Abpab in inbred strains may be due to a M. m. musculus contribution, perhaps via oriental fancy mice bred to European mice in the early lines leading to the common inbred strains. The relatively common occurrence of the ABP a type in other Mus species leads us to conclude that it is the ancestral type in mice. Further, the observation of what amounts to unique alleles in the three different subspecies indicates that microevolution of the protein has occurred. In a broader survey, ABP was also found in the salivas of Murid and Cricetid rodents generally. These findings suggest that ABP has an important functional role in rodent salivas.

Deposition of PrP amyloid in cerebral vessels in conjunction with neurofibrillary lesions is the neuropathologic hallmark of the dementia associated with a stop mutation at codon 145 of PRNP, the gene encoding the prion protein (PrP). In this disorder, the vascular amyloid in tissue sections and the approximately 7.5-kDa fragment extracted from amyloid are labeled by antibodies to epitopes located in the PrP sequence including amino acids 90-147. Amyloid-laden vessels are also labeled by antibodies against the C terminus, suggesting that PrP from the normal allele is involved in the pathologic process. Abundant neurofibrillary lesions are present in the cerebral gray matter. They are composed of paired helical filaments, are labeled with antibodies that recognize multiple phosphorylation sites in tau protein, and are similar to those observed in Alzheimer disease. A PrP cerebral amyloid angiopathy has not been reported in diseases caused by PRNP mutations or in human transmissible spongiform encephalopathies; we propose to name this phenotype PrP cerebral amyloid angiopathy (PrP-CAA).

Pelizaeus-Merzbacher disease (PMD) is a human X chromosome-linked dysmyelination disorder of the central nervous system for which the genetic defect has not yet been established. The jimpy mutation jp of the mouse is an X chromosome-linked disorder of myelin formation. The mutation is at an intron/exon splice site in the mouse gene for proteolipid protein (PLP). With the jimpy mouse mutation as a precedent, we focused our attention on the human PLP gene, which is found at Xq22. The polymerase chain reaction was used to amplify the exons of the PLP gene of an affected male from a large Indiana PMD kindred. DNA sequencing showed a C----T transition at nucleotide 40 of the second exon. An affected third cousin also showed this sequence variation, while two unaffected male relatives (sons of an obligate carrier female) had the normal cytidine nucleotide. Allele-specific oligonucleotides were used to generate data for linkage studies on the above mentioned PMD kindred. Our results show tight linkage (theta = 0) of PMD to PLP with a lod (logarithm of odds) score of 4.62. In six other unrelated PMD kindreds, only the normal-sequence oligonucleotide hybridized, which indicates genetic heterogeneity. The radical nature of the predicted amino acid change (proline to leucine), suggests that the PMD-causing defect may have been delineated in one kindred.

Azzarelli et al reported an Indiana kindred affected by a hereditary disorder, characterized clinically by ataxia, parkinsonism, and dementia. Recently, we studied neuropathologically the 3rd and 4th cases that came to autopsy among the patients of this family. As in 2 patients examined previously, amyloid plaques were widespread throughout the cerebrum and the cerebellum, whereas neurofibrillary tangles were numerous in the cerebral cortex, the hippocampus, and the substantia innominata. Amyloid plaques were not recognized by polyclonal antibodies against the Alzheimer's disease amyloid A4 protein, but did contain epitopes recognized by antibodies against a prion protein. Spongiform changes were occasionally observed and were mild. Our findings indicate that this familial disorder is a form of or is related to Gerstmann-Sträussler-Scheinker disease. The consistent presence of numerous neurofibrillary tangles may be important in differentiating a distinct subgroup of patients with familial Gerstmann-Sträussler-Scheinker disease, and indicates that a disturbance of the cytoskeleton might be part of the neuronal pathology of Gerstmann-Sträussler-Scheinker disease.

We present the clinical findings in affected members of a large kindred with Gerstmann-Sträussler-Scheinker disease. Sixty-four patients exhibited progressive ataxia, dementia, and parkinsonian features. Inheritance appears to be autosomal dominant. Impaired smooth-pursuit eye movements, defective short-term memory, clumsiness of the hands, and ataxia of gait develop in the late 30s to early 60s. Eye movement abnormalities are characteristic of cerebellar dysfunction. Dementia progresses gradually over several years. Later, rigidity and bradykinesia appear and, at this stage, there is often psychosis or severe depression with rapid weight loss. Death occurs in 6 months to 2 years after onset of rigidity. Magnetic resonance imaging in 2 affected individuals showed cerebellar atrophy. There is decreased T2signal in the basal ganglia, consistent with iron deposition.

We describe a system of transgenic human cell lines that detects and identifies specific point mutations at defined positions within a gene. The target transgenome is a mouse adenine phosphoribosyltransferase (APRT) gene rendered nonfunctional by introduction of a substitution at either of two bases that comprise a splice acceptor site. Reversion at a mutated site results in the expression of wild-type mouse APRT and consequent growth of APRT+ transgenic cell colonies. Site-specific reversion to wild-type sequence is confirmed by regeneration of a previously destroyed diagnostic Pst I site. Two independent cell clones, each with mutant transgenomes bearing an A----G transition, exhibited an up to 7500-fold, dose-dependent induction of reversion following treatment with ethyl methanesulfonate. Treatment of these clones with 2-aminopurine resulted in no induction of revertants. In contrast, another transgenic cell clone, bearing a G----A transition, reverted as a consequence of 2-aminopurine, but not ethyl methanesulfonate, treatment. These data confirm for human cells the proposed mechanisms of action of these mutagens and provide evidence for the utility of our site-specific reversion method for mutagenesis studies.